We report passive harmonic mode locking of a soliton Yb fiber laser at repetition rates continuously scalable up to $1.5\mathrm{GHz}$ . The laser generates transform-limited $500\mathrm{fs}$ pulses, with pulse energies of $30–100\mathrm{pJ}$ . At the 31st harmonic $\left(1.3\mathrm{GHz}\right)$ , the cavity supermodes are suppressed by $35\mathrm{dB}$ , and the pulse-to-pulse timing jitter is $6\mathrm{ps}$ .